3. 30 Degree Narrow Belt Sorter (rate range: 60 to 110 PPM targeted range)
There’s one patented narrow-belt sorter design that can achieve rates above 100 PPM due to a unique divert mechanism and patented controls logic. This design raises and lowers each row of divert wheels independently in a wave action. This allows a significant reduction in the amount of gap required between products. This, in turn, substantially increases the throughput rate.
Medium-Throughput Sorters—Between 20 And 60 PPM
1. 24 Volt Direct Current (VDC) Sorter (Rate range: 0 to 40 PPM)
The 24 VDC boasts significantly reduced power consumption and does not require expensive induction equipment. Different from standard AC voltage systems, product accumulation is also possible between divert points, as well as on inclines or declines. This is very helpful in shipping sorter applications.
With very low noise, fewer safety considerations, reduced air compressor requirements, low spare parts inventory, lower maintenance costs and easy to maintain equipment, 24 VDC systems are an excellent choice to consider whenever throughput rates are below 40 PPM.
The disadvantage is that the initial cost may be higher, although it varies depending upon manufacturer. The divert mechanism is typically either pivoting or pop-up style wheels, similar to those described below. Or at a throughput rate of less than 20 PPM, one can also use a 90 degree transfer divert. Take-away methods are 24 VDC powered spurs, gravity conveyors or gravity chutes.
2. Pivot-Wheel Sorters (rate range: 40 to 70 PPM targeted range)
With pivot-wheel sorters, the product is conveyed on top of a belt that is the full conveyor width and at each divert location is a divert section with several smaller divert wheels that spin about 40 percent faster than the speed of the belt. As the product nears the divert spur, the sorter uses cams or pistons to rotate/pivot these wheels to divert product at a 30 degree angle. The rotated wheels cause the product to divert off onto a powered or gravity spur, or a chute.
Often times, a slave-driven, powered spur is the preferred choice for a few reasons. First, it uses very little electricity. Second, since there is no motor, the maintenance requirements are significantly lower than for a motor-driven powered spur.
Third, the slave-driven power will help divert the product more reliably and with fewer jams than the gravity spur or chute. This pivot style sorter also tends to divert product more reliably than the pop-up wheel sorter (with one exception; See below). Although bi-directional sorting is possible, additional equipment is required, which may contribute to frequent jams when a variety of sizes, weights and products are sorted.
3. Pop-Up Wheel Sorters (rate range: 40 to 70 PPM targeted range)
This sorter is quite similar to the pivot-wheel sorter. Instead of rotating/pivoting, however, the wheels are preset to a specific angle and then are very quickly raised and lowered using cams or pistons to divert the product. The only other difference is that a pivot-wheel sorter tends to have slightly fewer nuisance jams. This seems to become more evident when conveying product without a firm, flat bottom surface, such as lower grade corrugated or dimpled totes.
LOW-THROUGHPUT SORTERS—BETWEEN 0 AND 20 PPM
1. 90 Degree Transfer Sorters (rate range: 0 to 20-plus PPM targeted range)
The two main types of 90 degree transfer sorters are lineshaft and narrow belt. Lineshaft sorters continue to lose market share due to their limitations versus other types of sorters and a reduction in their previous cost advantage. However, they are still frequently used in split-case (pick and pass) applications due to good space utilization, low-pressure accumulation capabilities and reduced power requirements.